This invention relates to a method for positioning a number of working implements, such as spray nozzles, screw joint tightening tools, spot welding electrodes, etc, relative to certain working or treatment points on a car body as the latter is supported by an overhead conveyor for travel between different working and assembly stations on a production line. The technique comprises a vertically movable base structure and a working implement carrying frame movably supported on the base structure.
In DE No. 33 34 047 there is disclosed a car body anticorrosion treatment device of the above type. According to this prior art equipment, the car body to be treated is positioned relative to a nozzle carrying frame by means of a number of conical dowels which are raised up against the car body to engage apertures in the latter. To make the car body centralize properly on the dowels it is lifted up by the latters such that it separates at least to some extent from the conveyor.
This known device is particularly adapted to production lines having floor mounted conveyors. However, in factories having overhead conveyors from which the car bodies hang down during their travel between the different working and assembly stations there will be a problem if using a device of this known type, because if the car body to be treated were lifted up it would temporarily loose its support on the conveyor, and when lowered down again after treatment there is a risk that the car body will come into disalignment with the conveyor. Thereby, the car body would loose its proper orientation when heading for the next station on the line.
The invention intends to solve the above problem and is characterized by the features stated in the claims.